The present invention is related to the field of thermal vaporizers for liquid formulations comprising volatile actives.
The use of so-called plug-in thermal vaporizers to dispense volatile actives is well known. Some known thermal vaporizers comprise a wick means inserted into a container with a reservoir of liquid volatile active, a heater unit and electric pins which are either fixed, as described in U.S. Pat. No. 4,467,177, or able to be rotated such that the wick can be orientated perpendicular to the ground, as described in U.S. Pat. No. 5,647,053, U.S. Pat. No. 5,290,546, U.S. Pat. No. 5,038,394, U.S. Pat. No. 5,095,647 and EP-A-0 962 132.
In the above-mentioned cases, the vaporizers rely on the air motion resulting from the heat rising from the heater unit and the natural dispersion properties of the volatile liquid to disperse the vapor within a defined area such as a room. The wick means comprises a wick formed in the shape of a rod that draws liquid from a refill container up and into a cylindrical gap formed at the center of a heater coil, through which the wick rod passes. Heat from the coil warms the rod, causing evaporation of the liquid, which is replenished through capillary action up the porous rod. In all cases, the heater unit is arranged to operate at one fixed pre-determined temperature.
There are plug-in units available that are designed to control the evaporation intensity by movement of either the container (such as a refill bottle) and wick in relation to the heater unit, as described in the above-mentioned EP-A-0 962 132 or by moving the heater unit in relation to the wick, as is the case with the commercially available air freshener retailed under the Ambi-Pur brand by Sara Lee. In these cases, the amount of evaporation is controlled by exposing more or less of the wick to the heater unit but the operating temperature of the heater unit is still fixed.
It is common for plug-in liquid vaporizer units to run at two distinct temperatures, depending on the end use of the product. Devices for dispensing an insecticide vapor tend to use ceramic or graphite-based wicks and run at temperatures typically in the region of 110-140 degrees centigrade, as is the case with the Kill-Paff(copyright) unit as marketed by Zelnova(copyright). Fragrance dispensing units, such as the Ambi-Pur(copyright) brand by Sara Lee(copyright), tend to run at lower temperatures, utilizing cellulose or fiber wicks. As a result of the different wicks and operating temperatures, separate heater units have customarily been specifically designed for each end use.
WO-A-97/39779 discloses a multiple electronic vaporizer for resins, which is provided with a plurality of heated hollow bodies, each hollow body reaching different temperatures according to the type of resin to be evaporated (such as incense, propolis and myrrh).
DE-A-37 01 499 discloses a thermal vaporizer arranged to heat tablets containing active substances. The device is arranged so that two tablets with different active substances (such as one tablet with a fragrance and another tablet with an insecticide) can be heated simultaneously, at different temperatures.
DE-A-33 45 134 and U.S. Pat. No. 4,588,874 also disclose thermal vaporizers for evaporating active substances in tablets. Here, the vaporizers include switches for allowing the vaporizers to be set to operate at different temperatures, n accordance with the active substance to be evaporated. The user is expected to manually operate the respective switch in order to select the correct temperature corresponding to the specific active substance to be evaporated. Of course, this implies a certain risk that the user may forget to set the switch to the correct position, whereby an incorrect heating temperature may be applied to a specific active substance.
In the case of a thermal vaporizer for an active substance housed in a bottle with a wick means, using a too high temperature (for example, for a fragrance dispensing bottle with wick) could cause damage to the wick. On the other hand, using a too low temperature for dispensing an insecticide could result in an ineffective release of the insecticide.
Thus, it would be desirable to reduce the risk for erroneous selection of the operating temperature.
The invention comprises a thermal vaporizer, a container and a thermal vaporizer assembly as defined in the independent claims. Some preferred embodiments of the invention are defined in the dependent claims.
A first aspect of the invention relates to a thermal vaporizer for a liquid formulation comprising a volatile active, said vaporizer comprising a housing having: a heater unit for evaporating the liquid formulation; a mounting for a container for the liquid formulation; a passage for a wick means to be heated by the heater unit; at least one outlet for evaporated volatile active; and an electrical contact connected to said heater unit.
The vaporizer further comprises:
means for selectively operating the heater unit at, at least, two different predetermined heating temperatures, including selecting means for selecting heating temperature, said selecting means including at least one first selecting means arranged to be selectively activated by the container.
By this way, it is achieved that the container, when applied to the vaporizer (preferably, when mounted in the mounting), may activate the first selecting means. This activation can be achieved by means of providing certain containers with special features or activating means so as to activate the first selecting means when the container is brought into a specific relation with the vaporizer, such as when the container is mounted into the mounting of the vaporizer. Thus, said certain containers (which may be, for example, containers for insecticides) will activate the first selecting means, whereas other containers (which may be, for example, containers for fragrances) will not activate said first selecting means. Thus, the heater unit will only operate at a specific predetermined temperature when a container is applied that has the special activating features or activating means. Examples of such activating means will be discussed in more detail later hereinbelow.
Thus, by means of the invention, it is achieved that the temperature at which the heater unit will operate will be switched over automatically when a specific type of container is applied to the vaporizer, for example, when such a container is mounted into the mounting. That is, the heater unit will be made to operate at a suitable temperature in accordance with the specific type of container used.
Thus, the thermal vaporizer according to the invention can be used for the dispensing of different volatile actives, such as insecticides and fragrances. Depending on the type of fragrance used, the container will or will not be provided with special activating features or activating means, so that the first selecting means will automatically be activated or not activated, in accordance with the specific container (and, thus, volatile active) used. Thus, as long as the correct container is used, there will be no danger (or, at least, a substantially reduced danger) that the heater unit could run at an incorrect temperature for a given volatile active.
The first selecting means can comprise, for example, a displaceable switch element arranged to be displaced by the container when the container is fixed into the mounting.
The first selecting means can also comprise one or more selectively interrupted electric circuits arranged to be closed by a metal (or equivalent) connector on the container when the container is fixed into the mounting. For example, the invention can comprise two incomplete or interrupted circuits whereby at least one of them is completed or closed by a metal connector forming part of the container (for example, of the neck, top or cap of the container) when the container is fixed into the mounting. In that case, the specific design of the metal connector of the container could determine whether a first one, a second one or both of the circuits be completed or closed, thus giving rise the different operating temperatures of the heater unit.
The heater unit can have an annular shape enclosing the passage for the wick means. The wick means can comprise, for example, a ceramic or graphite-based wick, attached to the container so that when the container is fixed into the mounting, the wick will extend through the above-mentioned passage.
The selecting means may further comprise further selecting means, such as a second selecting means for selecting, at least, an off operation mode and an on operation mode. By means of this second selecting means, the vaporizer can be turned off and on. However, in order to operate at a specific predetermined temperature, the vaporizer must not only be turned on but must also be triggered by means of the container activating the first selecting means, as outlined above.
The second selecting means can, for example, be arranged as an on-off switch arranged to be activated by the container when the container is fixed into the mounting (in this way, the heater unit will only be able to operate when a container is mounted in the vaporizer) or as an independent switch means mounted on the housing of the vaporizer and arranged to be operated manually by a user.
The second selecting means and the first selecting means can be arranged so as to make it possible to operate the heater unit at different predetermined temperatures. For example, the heater unit can be arranged to operate at a specific high temperature only when the first selecting means are activated by the container. The heater unit can further be arranged to operate at a low temperature when the second selecting means are in a first on operation mode position and the first selecting means are not activated by the container, at a medium temperature when the second selecting means are in a second on operation mode position and the first selecting means are not activated by the container; and at the specific high temperature only when the first selecting means are activated by the container. In this way, one can achieve that, for example, insecticide may not be released unless the first selecting means are activated by the container but fragrance can be released at two different temperatures (the low one and the medium one mentioned above), as desired by the user who sets the switch of the second selecting means accordingly.
The second selecting means could comprise a rocker switch having, for example, three settings of xe2x80x9coffxe2x80x9d, xe2x80x9clowxe2x80x9d and xe2x80x9chighxe2x80x9d and could be used to vary the temperature of the not activated setting of the first selecting means between two pre-set amounts (the above-mentioned low and medium temperatures). Thus, the vaporizer could operate at two levels of fragrance release and one level of insecticide release by the following combinations of the selecting means:
In this case, activating the first selecting means would render the two settings of the second selecting means redundant such that the second selecting means revert to an xe2x80x9con/offxe2x80x9d controller. However, it is also possible to utilize the low and high settings of the second selecting means to drive the insecticide emission at two pre-determined levels. Also other alternatives are possible within the scope of the invention. For example, the selecting means could be arranged so that the insecticide emission only takes place when the first selecting means are xe2x80x9cactivatedxe2x80x9d and the second selecting means are in a specific position, such as in the xe2x80x9clowxe2x80x9d position (and no: in the xe2x80x9chighxe2x80x9d position).
The means for selectively operating the heater unit may include, (at least, a first branch comprising a first resistor and, in series with said resistor, a circuit comprising a diode and a switch coupled in parallel, so that when said switch is in an open position, the supply voltage is applied over the diode and over the first resistor, and when the switch is in a closed position, the supply voltage is fully applied over the first resistor. The switch can be arranged to be in the open position when the first selecting means are not activated by the container and in the closed position when the first selecting means are activated by the container. The means for selectively operating the heater unit may further comprise a second branch comprising a second resistor, said second branch being arranged in parallel with said first branch, whereby said second selecting means are arranged so that depending on the position of said second selecting means, the supply voltage is applied selectively to the first branch or to the second branch so that heating is selectively performed by said first or by said second resistor.
The means for selectively operating the heater unit can also comprise at least one variable resistor, the effective resistance of which depends on a level of activation of the first selecting means.
The heater unit can comprise, for example, a wire-wound resistor or a ceramic block containing an array of discreet resistors or any similar device that generates heat on the application of an electrical supply.
The thermal vaporizer can be for a fragrance or an insecticide or both.
Preferable, the high temperature mentioned above corresponds to a temperature for vaporizing an insecticide, the low temperature corresponds to a temperature for low rate release of fragrance and the medium temperature to a temperature for high rate release of fragrance.
Another aspect of the invention relates to a container for the thermal vaporizer outlined above, whereby said container is provided with activating means for activating the first selecting means of the thermal vaporizer when the container is fixed into the mounting.
The activating means can, for example, be embodied by at least one protruding part of the container. The protruding part can, for example, be a molding.
The protruding part can be arranged at a suitable position of the container, for example, at a mouth portion of the container and/or at a neck or shoulder portion of the container.
The protruding part can form an integral part of the container (for example, in the case of a molded container, the protruding part can be molded integrally with the container). However, the protruding part can also be part of an independent element arranged to be attached to the container; for example, if the container is a bottle, the protruding part could be a collar to be put around the neck of the container, or it could be part of a cap portion of the container, for example, of an insert or cap holding the wick means.
The container can comprise such a closure or cap device including means for holding the wick means firmly in place. Preferably, the closure is not easily removable and cooperates with the wick means in such a way that the wick means is not easily removable from the container.
The container preferably comprises a part which cooperates in a known fashion with the mounting of the thermal vaporizer. For example, the container can be arranged to be fixed into the mounting by screw-thread engagement between an internally threaded portion of the mounting and an externally threaded portion of the container. Of course, also other arrangements for fixing the container into the mounting can be used, such as simple connections based on friction between the container and the mounting, bayonet-type connections, snap-fittings (such that the container is pushed, not screwed, into place), etc.
The protruding part could be, for example, a single, discreet feature or an annular raised portion that runs evenly around a vertical axis of the container (for example, a bottle). An annular feature would be particularly applicable to a screw container where the final orientation of the container may not be controllable. Thus, regardless of the final orientation of the container, the protruding part would still activate the first selecting means. Instead of a complete annular feature (that is, corresponding to an annular protruding portion running all around the container), it could be possible to use, for example, an arcuate protruding part corresponding to a segment of a circle.
For bottles that are snap-fitted or push-fitted (i.e. fitted into the unit in a specific orientation), the protruding part could be a single, discreet device. This would also give the advantage that the first selecting means could be arranged to be only accessible by a small orifice of sufficient size to only let the protruding part of the container in.
As suggested above, the first selecting means can be embodied as a rheostat or similar device, which varies the temperature of the heater unit depending on how far it is engaged. In that case, protruding parts with different dimensions could be provided, in order to displace the first selecting means by predetermined amounts corresponding to predetermined temperatures, depending on the final temperature desired. For example, the higher the protruding part, the higher the temperature at which the heater unit will be made to operate. In that case, the container could, for example, be a standard refill bottle, and collars or caps for said bottle could be provided having protruding parts with different dimensions.
The activating means may also comprise a metal connector or element, arranged so as to close an electrical circuit corresponding to the first selecting means; in that case, said metal connector could be embodied as an integral part of the container or as a separate device, associated with, for example, a collar device or a cap for the container.
Another aspect of the invention relates to a thermal vaporizer assembly comprising a thermal vaporizer and a container as outlined above.
The volatile actives of the thermally vaporizable liquid formulation are preferably selected from the group of fragrances, essential oils, insecticides, bactericides, repellents, drugs, herbicides and fungicides. These volatile actives may be carried by a volatile solvent, for example, water, ethanol, isoparaffin or glycol ethers.
For the purpose of providing a better understanding of the invention, some preferred embodiments of the invention will be described below with reference to the accompanying drawings. However, the scope of the invention should by no means be regarded as restricted to said preferred embodiments.